The invention is based on a machine tool as generically defined by the preamble to claim 1.
To make it advantageously possible to connect an insert tool to a drive shaft of a machine tool via a tool receptacle, it is known to fix the drive shaft using a locking device.
For angle grinders, a locking device is known that has a locking bolt, guided in rotationally fixed fashion with respect to the drive shaft in a housing, which bolt can be brought into engagement, via an actuation button, with a set of teeth rotationally fixedly connected to the drive shaft.
From European Patent Disclosure EP 0 904 896 A2, a grinding machine tool receptacle for a hand-held angle grinding machine is also known. The angle grinding machine has a drive shaft that has a thread on the side toward the tool.
The grinding machine tool receptacle also has a slaving means and a lock nut. For mounting a grinding wheel, the slaving means is slipped with a mounting opening onto a collar of the drive shaft and braced against a bearing face of the drive shaft by nonpositive engagement via the lock nut. The slaving means has a collar, extending axially on the side toward the tool, that on two radially opposed sides on its outer circumference has recesses that extend axially as far as a bottom of the collar. From each of the recesses, a respective groove extends on the outer circumference of the collar, counter to the driving direction of the drive shaft. The grooves are closed counter to the driving direction of the drive shaft and taper axially, beginning at the recesses, counter to the drive direction of the drive shaft.
The grinding wheel has a hub with a mounting opening, in which two opposed tongues are disposed, pointing radially inward. The tongues can be introduced axially into the recesses and then in the circumferential direction, counter to the driving direction, into the grooves. The grinding wheel is fixed by positive engagement in the grooves in the axial direction via the tongues and by nonpositive engagement by means of the tapering contour of the grooves. During operation, the nonpositive engagement increases as a consequence of reaction forces exerted on the grinding wheel, which act counter to the driving direction.
To prevent the grinding wheel from coming to a stop when the drive shaft is braked by the slaving means, a stopper, which is movably supported in the axial direction in an opening, is disposed in the region of a recess on the circumference of the collar. In a working position where the grinding wheel points downward, the stopper is deflected axially by gravity in the direction of the grinding wheel and closes the groove in the direction of the recess and blocks a motion of the tongue, located in the groove, in the driving direction of the drive shaft.
The invention is based on a tool receptacle, in particular for a hand-held angle grinding machine or a circular power saw, having a slaving device, by way of which an insert tool can be operatively connected to a drive shaft, and having a locking device, by way of which, with an actuation button, the drive shaft can be locked upon mounting and/or removal of the insert tool.
It is proposed that the actuation button is operatively connected in the direction of rotation to the drive shaft, and by way of the actuation button, for locking the drive shaft, at least one first part, operatively connected in the direction of rotation to the drive shaft, can be connected to a second part, which is rotationally fixed with respect to a rotational axis of the drive shaft. Because of the actuation button that rotates with the drive shaft in operation, it can be reliably prevented that the actuation button is misused to brake the drive shaft. Slowing down of the insert tool to a stop as a result of an unintended major braking moment with the attendant risk of injury can be reliably avoided, and wear of the locking device can be reduced.
The embodiment of the invention can be employed in various tool receptacles that appear useful to one skilled in the art. It is especially advantageous, however, if the insert tool is operatively connectable to the slaving device via at least one detent element, supported movably counter to a spring element, which detent element snaps into place in an operating position of the insert tool and fixes the insert tool by positive engagement. Because of the positive engagement, an especially secure fastening of the insert tool can be attained. Moreover, with the movably supported detent element upon the installation of the insert tool, a major deflection of the detent element can be made possible, as a result of which on the one hand a major overlap between two corresponding detent elements and an especially secure positive engagement can be achieved, and on the other, a readily audible snapping-engagement noise can be achieved, which advantageously indicates to the user that the snap-in operation has been completed as desired.
In addition, a simple, economical, tool-less fast-action clamping system can be created, in which advantageously the movement of the detent element and/or the movement a component that is moved with the detent element can be utilized for the locking device of the drive shaft, which can be achieved especially simply in structural terms if the detent element is displaceably supported in the axial direction counter to the spring element. One or more components can be used to secure the insert tool and additionally for the locking device, and as a result additional components, installation space, and assembly effort and expense can be economized upon, especially if the detent element and/or a component movably supported with the detent element is connectable by the actuation button to the second part, which is rotationally fixed with respect to the rotational axis of the drive shaft, and the drive shaft is lockable in the circumferential direction.
Also in the tool receptacle proposed, in the installation and removal only slight torques to be absorbed by the locking device occur, and as a result the locking device can be designed as especially light in weight and economical.
The detent element can fix the insert tool by positive engagement either directly or indirectly via an additional component, for instance via a detent lever or tappet and the like that is coupled with the detent element and is supported rotatably and/or axially displaceably. The detent element can fix the insert tool by positive engagement directly and/or indirectly in various directions, such as the radial direction, axial direction, and/or especially advantageously the circumferential direction. It is also possible that as a result of the positive-engagement fixation of the insert tool with the detent element in a first direction, such as the radial direction, the insert tool is fixed by positive engagement in a second direction, such as the circumferential direction, by means of a component that is separate from the detent element.
The movably supported detent element can be embodied in various forms that appear useful to one skilled in the art, for instance as an opening, protrusion, peg, bolt and the like, and can be disposed on the insert tool and/or on the slaving device. The detent element itself can be supported movably in a component in a bearing location, for instance in a flange of the slaving device or in a tool hub of the insert tool. However, the detent element can advantageously also be solidly connected by nonpositive, positive and/or material engagement to a component supported movably in a bearing location, or can be embodied integrally with such a component, for instance with a component supported on the drive shaft or with a tool hub of the insert tool.
Also by means of the positive engagement, an advantageous encoding can be achieved, so that with the tool receptacle, only the insert tools intended can be secured. The slaving device can be embodied at least in part as a detachable adapter part, or it can be connected nondetachably to the drive shaft by nonpositive, positive and/or material engagement.
With the tool receptacle, various insert tools that appear useful to one skilled in the art can be secured, such as insert tools of an angle grinder for severing, grinding, rough-machining, brushing and so forth. A tool receptacle of the invention can also be used to secure a grinding plate of eccentric grinding machines.
In a further feature, it is proposed that the detent element and/or the component movably supported with the detent element is connectable by positive engagement to the second part that is rotationally fixed with respect to the rotational axis of the drive shaft, as a result of which, with little expenditure of force, secure locking of the drive shaft can be attained in a comfortable way. In principle, however, a nonpositive locking is also conceivable, especially in the tool receptacle of the invention, in which only slight torques have to be absorbed by the locking device in the installation and removal of the insert tool. In the event of an unintended actuation of the actuation button during operation, less wear is furthermore achievable compared with a positive-engagement locking device.
If the detent element can be released from its detent position by an unlocking button, then an independent release of the detent connection which could for instance be caused by a braking moment can be reliably prevented, thus enhancing safety. Operation of the insert tool in two circumferential directions can be made possible in principle, making it more convenient to install and remove the insert tool.
In a further feature of the invention, it is proposed that the actuation button of the locking device and the unlocking button are embodied integrally. Additional components, weight, installation effort and expense can all be economized on, and in particular convenience can be enhanced and usage can be simplified. By actuating the actuation button in one direction, a user can unlock the insert tool and at the same time lock the drive shaft.
Advantageously, at least one detent element, extending in the axial direction, is secured in a component that is supported displaceably on the drive shaft counter to a spring element. One and especially advantageously more than one detent elements can be guided well on the drive shaft over a large bearing area. Tilting of the detent elements and motion of the detent elements relative to one another can be reliably avoided, and with a spring element, which can advantageously be disposed rotationally symmetrically and concentrically, a desired spring force for a detent operation can be achieved. The component and/or the detent elements secured in the component can advantageously also be connected to the second part, which is rotationally fixed with respect to the rotational axis of the drive shaft, and torques that occur during the installation and removal can advantageously be absorbed.
If at least one detent element is formed integrally on a disklike component and/or if the first part, operatively connected to the drive shaft in the direction of rotation, is integrally formed onto a disklike component and/or if at least two elements for fixation of the insert tool in the axial direction are integrally formed onto a disklike component, then additional components and installation effort and expense can be saved. Furthermore, press-fitted connections between individual components with the attendant weak points can be avoided.